or Diocese, the circuit or extent of the jurisdiction of a Bishop.—The word is formed from the Greek διοικητής, government, administration; formed of διοικέω, which the ancient glossaries render administro, moderator, ordino; hence διοικητής τῆς πόλεως, the administration or government of a city.

Diocese is also used in ancient authors, &c., for the province of a metropolitan.

Diocese, διοικητής, was originally a civil government, or prefecture, composed of divers provinces.

The first division of the empire into dioceses is ordinarily ascribed to Constantine; who distributed the whole Roman state into four, viz. the diocese of Italy, the diocese of Illyria, that of the east, and that of Africa. And yet, long before Constantine, Strabo, who wrote under Tiberius, takes notice, lib. xiii. p. 432, that the Romans had divided Asia into dioceses; and complains of the confusion such a division occasioned in geography, Asia being no longer divided by people, but by dioceses, each whereof had a tribunal or court, where justice was administered. Constantine, then, was only the institutor of those large dioceses, which comprehended several metropoles and governments; the former dioceses only comprehending one jurisdiction or district, or the country that had resort to one judge, as appears from this passage in Strabo, and (before Strabo) from Cicero himself, lib. iii. epist. ad famil. 9. and lib. xiii. ep. 67.

Thus, at first a province included divers dioceses; and afterwards a diocese came to comprise divers provinces. In after times the Roman empire became divided into 13 dioceses or prefectures; though, including Rome, and the subburbicary regions, there were 14. These 14 dioceses comprehended 120 provinces: each province had a proconsul, who resided in the capital or metropolis; and each diocese of the empire had a consul, who resided in the principal city of the district.

On this civil constitution, the ecclesiastical one was afterwards regulated: each diocese had an ecclesiastical vicar or primate, who judged finally of all the concerns of the church within his territory.

At present there is some further alteration: for diocese does not now signify an assemblage of divers provinces; but is limited to a single province under a metropolitan, or more commonly to the single jurisdiction of a bishop.

Gul. Brit. affirms diocese to be properly the territory and extent of a baptismal or parochial church; whence divers authors use the word to signify a simple parish. See Parish.